1. Field of the Invention
The present disclosure relates to an image forming apparatus, a motor control apparatus, and a method of controlling a motor, and more particularly to an image forming apparatus, a motor control apparatus, and a method of controlling a motor, which can sense a load of a step motor and vary constant current supplied to the step motor according to the sensed load.
2. Description of the Related Art
An image forming apparatus is an apparatus which performs generation, printing, reception, and transmission of image data, and representative examples thereof may be a printer, a copy machine, a facsimile, and a multifunction peripheral (MFP) in which functions of the above-described devices are combined.
In such an image forming apparatus, motors for performing various functions, such as conveyance of print sheets and feeding of print sheets, are used. Recently, as optional units that perform various functions, such as an ADF (Auto Document Feeder) unit, a finisher unit, an HCF (High Capacity Feeder) unit, and a DCF (Double Capacity Feeder) unit, can be attached to the image forming apparatus, the number of motors that can be used in the image forming apparatus is gradually increased.
In a recent image forming apparatus, a step motor (or a pulse motor or a stepping motor) is used to precisely control the conveyance of print sheets. Here, the step motor is a motor that moves by predetermined angles to correspond to the number of input pulses. Since the number of input pulses is completely in proportion to a rotating angle of the motor, the rotating angle of the motor can be accurately controlled.
Although the step motor as described above can be driven in various driving methods, a constant current driving method has been widely used. Here, the constant current driving method is a method to make constant current that is always a constant flow to a coil of the step motor regardless of a load that is applied to the step motor.
On the other hand, if the load of the system is increased and a necessary current amount becomes larger than the fixed inflow current amount, the step motor may be stepped out, and in the constant current driving method in the related art, a current amount that is larger than the necessary current amount is supplied to the step motor.
However, if the current amount that is larger than the necessary current amount is supplied, the remaining current amount (current that is not consumed for motor driving), causes vibration, noise, and heating of the motor. Further, due to the oversupplied motor inflow current, unnecessary power consumption may occur.
Further, a motor having a larger capacity than the motor having the rated capacity, which is necessary for actual use, should be used, and this may cause the material cost of the motor components to be increased. If the load is increased due to output abnormality although a large current amount is supplied to the step motor, it is still possible that the step motor is stepped out.